Delusional Disorders

Delusional disorder may be classified according to Diagnostic and Statistical Manual based on content of the delusions into seven subtypes: erotomanic, grandiose, jealous, persecutory, somatic, mixed, and unspecified. As suggestive of its title, delusional disorder requires the presence of at least one delusion that lasts for at least one month in duration. It is important to note that should an individual experience a delusion, but, has also experienced either hallucinations, disorganized speech, disorganized or catatonic behavior, or negative symptoms (additional criteria of schizophrenia), they should not be diagnosed with delusional disorder as their symptoms are more aligned with a schizophrenia diagnosis. Unlike most other schizophrenia related disorders, daily functioning is not overly impacted due to the delusions. Additionally, if symptoms of depressive or manic episodes present during delusions, they are typically brief in duration compared to the duration of the delusions.

Apart from their delusions, people with delusional disorder may continue to socialize and function normally; their behavior does not stand out as odd or bizarre. However, their preoccupation with delusional ideas can disrupt their lives.

Diagnosis of a specific type of delusional disorder can sometimes be made based on the content of the delusions. The Diagnostic and Statistical Manual of Mental Disorders (DSM) enumerates seven types:
Subtypes of delusional disorder Description

  • The patient believes that another person is secretly in love with her or him.
  • The person which patient believes is in love may be famous or have some kind of higher status, usually not part of the patient’s social circle, and not likely to be attainable.
  • Affected individuals may attempt to communicate with the object of their affection and may attempt to meet him/her in person. Such effort can lead to stalking in some cases, with some risk for assaultive behavior.
  • Expressions of love may be intense, and rejections by the loved person is interpreted oddly as affirmations of love to deflect suspicions or jealousy from the loved person’s spouse. Other names of erotomanic delusional disorder: DeClerambault syndrome, erotomania, psychose passionelle.


  • The patient believes he/she has special prominence or talent, major achievements, or unusual fame.
  • Features of the patient’s thinking may suggest the grandiosity associated with mania, however in the delusional disorder, the mood disturbance and behaviors characteristic of mania are not present.


  • The delusional theme is the patient believes that a spouse or lover is unfaithful and finds "evidence" to support the delusion, accuses him or her, and relentlessly tries to substantiate the offense.
  • The delusion of jealousy can lead to aggressive, possibly violent, and threatening behavior, including homicide and suicide. In some cases delusional jealousy and its disruptive impact may only improve through separation from the suspected unfaithful partner. Other names of jealous delusional disorder: pathological or morbid jealousy, Othello syndrome, conjugal paranoia.


  • The patient is typically preoccupied by a delusion that he or she is being persecuted, potentially harmed, or conspired against.
  • His/her resulting actions are generally consistent with these concerns; they are well planned and executed, and carried out with emotional vigor and determined effort.
  • The individuals with persecutory delusions may resort to the courts and even to violence to right the wrongs directed at them.


  • The patient believes that something awful is wrong with his/her body. There are several forms: that one is ill with undiagnosed disease; that one is infested with parasites or insects (delusional parasitosis); or that parts of the body are ugly, misshapen, or emanate a foul odor.
  • Individuals generally go from one doctor to another, specialist to specialist, usually disappointed by the failure to detect and diagnose the medical problem that haunts them. Suicide may be a risk, thought due to frustration and lack of effective clinical intervention. Other names of somatic delusional disorder: hypochondriacal delusion, monosymptomatic hypochondriasis.


  • More than one delusional theme predominates.


  • The dominant delusional belief cannot be clearly determined or is not described by the subtypes above.

  • Other notable differences between the DSM-IV and DSM-5 diagnostic criteria are a clearer demarcation of delusional disorder in DSM-5 from psychotic variants of obsessive compulsive disorder and body dysmorphic disorder that is made explicit with a new exclusion criterion. Such a presentation must not be better explained by obsessive compulsive or body dysmorphic disorder with lack of insight/delusional beliefs.

  • Shared delusional disorder is no longer separated from delusional disorder as in DSM-IV. If the criteria for delusional disorder are met, delusional disorder is the appropriate diagnosis. If that diagnosis cannot be made yet shared delusional beliefs are present, the appropriate diagnosis is "other specified schizophrenia spectrum and other psychotic disorder."
  • Among them persecutory and jealous subtypes are the most common, and erotomanic and grandiose are the least common.


The cause of delusional disorder is unknown, but genetic, biochemical, psychological, and environmental factors may play a significant role in its development. Delusional disorder is currently thought to be on the same spectrum or dimension as schizophrenia, but people with delusional disorder, in general, may have less symptomatology and functional disability. The etiology of delusional disorder is unknown, and several difficulties exist in conducting research in this area:


  • According to the DSM-5, on an average, global function is generally better in delusional disorder than that observed in schizophrenia. Although the diagnosis is generally stable, a proportion of individuals go on to develop schizophrenia. Delusional disorder has a significant familial relationship with both schizophrenia and schizotypal personality disorder.

  • There might be a genetic factor involved in the development of delusional disorder, which is suggested by the fact that delusional disorder is more common in people who have family members with delusional disorder or paranoid personality traits. It is also believed that, as with other mental disorders, a tendency to develop delusional disorder might be passed on from parents to their children. Close relatives of persons with delusional disorder do not have higher rates of schizophrenia, schizoaffective disorder or mood disorder compared to relatives of non-delusional persons.

  • Studies comparing activity of different regions of the brain in delusional and non-delusional research participants have yielded data about differences in the functioning of the brains between members of the two groups. These differences in brain activity propose that persons neurologically with delusions tend to react as if threatening conditions are consistently present whereas non-delusional persons only show such patterns under certain kinds of conditions where the interpretation of being threatened is more accurate. With the evidence of brain activity and family heritability, a strong chance exists that there is a biological aspect to delusional disorder.

  • Some studies have found that compared with normal participants, patients with delusional disorder showed abnormalities of voluntary saccadic eye movements and smooth pursuit eye movements, a dysfunction similar to that seen in patients with schizophrenia.

Biochemical factors

  • Biological factors may play a role in the development of delusional disorder, as delusions are associated with a wide range of nonpsychiatric medical conditions. Among patients with neurologic disorders such as head injury, dementia, and seizures, problems with the basal ganglia and temporal lobe are most commonly associated with delusions.
  • Some people with delusional disorders may have an imbalance in neurotransmitters, the chemicals that send and receive messages to the brain. Hyperdopaminergic states have been implicated in the development of delusions. In some studies an increased prevalence of a polymorphism at the D2 receptor gene at amino acid 311 (cysteine-for-serine substitution) among individuals with delusional disorder have been reported, particularly in those with persecutory delusions.

  • Individuals that had more TCAT repeats within the first intron of the tyrosine hydroxylase gene had higher levels of homovanillic acid, although it is unclear if they corrected for multiple statistical comparisons. Some studies have found that compared with normal participants, patients with delusional disorder showed abnormalities of voluntary saccadic eye movements and smooth pursuit eye movements, a dysfunction similar to that seen in patients with schizophrenia.

Environmental factors

Evidence suggests that delusional disorder can be triggered by stress. Alcohol and drug abuse also might contribute to the condition. People who tend to be isolated, such as immigrants or those with poor sight and hearing, appear to be more vulnerable to developing delusional disorder.

Psychological factors

It is suggested that persons with delusions selectively attend to available information, which appears to overlap with hypochondriacal patient populations. They attribute negative events to external personal causes, make conclusions based on insufficient information, and have difficulty in envisaging others’ intentions and motivations. Patients with delusional disorder make probability decisions based on fewer data compared with normal controls. Despite using fewer data, they are as certain as controls regarding the accuracy of their decisions.

  • The two neuropsychological models proposed for schizophrenia may also have some validity in delusional disorder.

    • A cognitive bias model (CBM) proposes that paranoia is a defense to protect a fragile self-esteem, against thoughts that threaten the idealized self. Positive events are attributed to the self whereas negative events are ascribed to the external environment.
    • The cognitive deficit model (CDM) focuses on cognitive impairments and distortions of threat evaluating mechanisms as the cause for delusion formation.



Treatment Principles of Delusional Disorder include the following:

Establish a therapeutic alliance and negotiate acceptable symptomatic treatment goals. Start where "the patient is at," and offer empathy, concern, and interest in the experiences of the individual
Avoid direct confrontation of the delusional symptoms to enhance the possibility of treatment compliance and response
Consider the impact of culture for treatment planning
Use medication judiciously to target core symptoms and associated problems (eg, anger)
Use outpatient treatment unless there is potential for harm or violence
Tailor treatment strategies to the individual needs of the patient and focus on maintaining social function and improving quality of life
Recognize and treat coexisting psychiatric disorders
Inpatient hospitalization should be considered if a patient’s delusions cause him or her to be a threat to self, others, or if he or she is deemed to be gravely disabled


  • Treatment of patients with delusional disorder with antipsychotic medication requires careful effort because of the patient’s denial of illness. It is particularly important to discuss and provide the patient with information about how the antipsychotic medication would be useful, for what target symptoms, what are possible side effects of antipsychotics, and the likely length of treatment of the delusional disorder.
  • An antipsychotic agent with as few side effects as possible such as ariprazole or ziprasidone should be used.
  • Start the medication at a low dose and increase the dose gradually over a several days or weeks to assure tolerability.
  • Once a therapeutic dose is achieved, examine for evidence of response at two weeks before changing the medication or increasing the dose further.
  • Olanzapine and risperidone are the most common atypical antipsychotics used for the treatment of delusional disorder. Five case reports of individuals with delusions presumably refractory to previous antipsychotic treatment have reported that clozapine was associated with a decrease in symptoms associated with the delusion and an improved quality of life, although the central delusional theme persisted. However, some cases of delusional disorder appear refractory even to clozapine treatment.
  • Antidepressants have been successfully used for the treatment of primarily somatic type of delusional disorder. Various case reports have showed improvement of delusional disorder with selective serotonin reuptake inhibitor (SSRI) and clomipramine treatments. A single case report of successful ECT use for somatic delusions exists. A standard trial of an antipsychotic or, for somatic delusions, an SSRI at starting doses is commonly used to treat psychotic or mood disorders.

Psychosocial interventions

Any psychiatric treatment of delusional disorder should incorporate the following psychotherapeutic principles:

  • Alliance building
  • Education
  • Support
  • Recognition of the challenges inherent in treating these patients.

For patients who deny that their concerns are delusional, a supportive approach to psychotherapy, with a verbally and listening supportive strategy intended to ease distress, is helpful. However, there have been no clinical trials of specific psychosocial interventions for delusional disorder. The following therapies have been suggested for the delusional disorder:

  • Cognitive-behavioral therapy
  • Core family therapy
  • Supportive therapy

Cognitive-behavioral therapy

  • Psychotherapy for patients with delusional disorder can include cognitive therapy which is conducted with the use of empathy. During the process, the therapist can ask hypothetical questions in a form of therapeutic Socratic questioning. This therapy has been mostly studied in patients with the persecutory type. The combination of pharmacotherapy with cognitive therapy integrates treating the possible underlying biological problems and decreasing the symptoms with psychotherapy as well. Psychotherapy has been said to be the most useful form of treatment because of the trust formed in a patient and therapist relationship. Individual psychotherapy is recommended rather than group psychotherapy, as patients are often quite suspicious and sensitive. The therapist is there for support and must not show any signs implying that the patient is mentally ill.
  • The cognitive-behavioral therapy aims to identify and address patient features believed to be associated with delusions, such as data gathering biases, interpersonal sensitivity, worry, insomnia, and reasoning style, factors thought to influence how a delusional patient interprets evidence pertinent to delusions or how they considers alternative explanations for the phenomena.
  • Discussion and analysis of the patient’s explanations for delusional ideas are practical techniques aimed at breaking down the conviction and emotional underpinnings that maintain the idea.
  • CBT has not been formally tested in patients with delusional disorders. Preliminary trials and case reports that included patients with delusional disorders have not been found to be sufficient to evaluate CBT’s efficacy. However, CBT produced more of an impact when compared to attention placebo control (APC) on strength of conviction, positive actions of beliefs, and affect relating to belief, which suggest that CBT is a successful means of treating delusional disorder.

Supportive psychotherapy

In supportive psychotherapy, the clinician attempts to gain insight into the painful quality of the patients’ experiences with delusional disorder and connect with the patient in these areas with understanding and suggestions aimed at reducing discomfort. Supportive therapy has also been shown to be helpful. Its goal is to facilitate treatment adherence and provide education about the illness and its treatment. Furthermore, providing social skills training has helped many persons. It can promote interpersonal competence as well as confidence and comfort when interacting with those individuals perceived as a threat.

Involuntary treatment

In patients with delusional disorder who are at serious risk of harming others, involuntary treatment with antipsychotic medication may have a role. Clinical decisions regarding involuntary treatment are subject to legal regulations that vary by country and locality.

Insight oriented therapy

Insight-oriented therapy is rarely indicated or contraindicated; yet there are reports of successful treatment. Its goals are to develop therapeutic alliance, containment of projected feelings of hatred, impotence, and badness; measured interpretation as well as the development of a sense of creative doubt in the internal perception of the world. The latter requires empathy with the patient's defensive position.

DSM-V Diagnostic Criteria for Delusional Disorder 

  • A. The presence of one (or more) delusions with a duration of 1 month or longer.


  • B. Criterion A for schizophrenia has never been met.

Note: Hallucinations, if present, are not prominent and are related to the delusional theme (e.g., the sensation of being infested with insects associated with delusions of infestation).


  • C. Apart from the impact of the delusion(s) or its ramifications, functioning is not markedly impaired, and behavior is not obviously bizarre or odd.


  • D. If manic or major depressive episodes have occurred, these have been brief relative to the duration of the delusional periods.


  • E. The disturbance is not attributable to the physiological effects of a substance or another medical condition and is not better explained by another mental disorder, such as body dysmorphic disorder or obsessive-compulsive disorder.

Specify whether:

Erotomanie type: This subtype applies when the central theme of the delusion is that another person is in love with the individual.


Grandiose type: This subtype applies when the central theme of the delusion is the conviction of having some great (but unrecognized) talent or insight or having made some important discovery.


Jealous type: This subtype applies when the central theme of the individual’s delusion is that his or her spouse or lover is unfaithful.


Persecutory type: This subtype applies when the central theme of the delusion involves the individual’s belief that he or she is being conspired against, cheated, spied on, followed, poisoned or drugged, maliciously maligned, harassed, or obstructed in the pursuit of long-term goals.


Somatic type: This subtype applies when the central theme of the delusion involves bodily functions or sensations.


Mixed type: This subtype applies when no one delusional theme predominates.


Unspecified type: This subtype applies when the dominant delusional belief cannot be clearly determined or is not described in the specific types (e.g., referential delusions without a prominent persecutory or grandiose component).

Specify if:

With bizarre content: Delusions are deemed bizarre if they are clearly implausible, not understandable, and not derived from ordinary life experiences (e.g., an individual’s belief that a stranger has removed his or her internal organs and replaced them with someone else’s organs without leaving any wounds or scars).

Specify if: The following course specifiers are only to be used after a 1-year duration of the disorder:

First episode, currently in acute episode: First manifestation of the disorder meeting the defining diagnostic symptom and time criteria. An acute episode is a time period in which the symptom criteria are fulfilled.
First episode, currently in partial remission: Partial remission is a time period during which an improvement after a previous episode is maintained and in which the defining criteria of the disorder are only partially fulfilled.

First episode, currently in full remission: Full remission is a period of time after a previous episode during which no disorder-specific symptoms are present.
Multiple episodes, currently in acute episode


Multiple episodes, currently in partial remission


Multiple episodes, currently in full remission


Continuous: Symptoms fulfilling the diagnostic symptom criteria of the disorder are remaining for the majority of the illness course, with subthreshold symptom periods being very brief relative to the overall course.



Specify current severity:

Severity is rated by a quantitative assessment of the primary symptoms of psychosis, including delusions, hallucinations, disorganized speech, abnormal psychomotor behavior, and negative symptoms. Each of these symptoms may be rated for its current severity (most severe in the last 7 days) on a 5-point scale ranging from 0 (not present) to 4 (present and severe).
Note: Diagnosis of delusional disorder can be made without using this severity specifier.


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